How to reproduce:
1. Start a new project
2. Create an empty GameObject
3. Add a SpriteRenderer component
4. Drag the GameObject to the project window to create a prefab
5. Select GameObject in hierarchy
6. Now select the "Sorting Layer" property and choose "Add Sorting Layer"
7. Create a new sorting layer
8. Notice that you have selected a different sorting layer in your prefab instance
than the one from the prefab, however, the corresponding editor does not
draw the attribute as BOLD font like it used to be.

Also, you can not right-click the "Sorting Layer" property and choose
"Revert to Prefab" (there is no context menu).

Same issue for the "Material" property in the SpriteRenderer editor